a = ['hello', 'world', 1, 2, 3]
for i in range(0, len(a)):
    print(i, '-->', a[i])
print()
for index, item in enumerate(a):
    print(index, item)  # index  是序号，不是索引
print()
# 手动修改序号的起始值
for index, item in enumerate(a, start=1):  # start可以不写
    print(index, item)